TW201429301A - Dimming circuit and lighting device using the same - Google Patents

Dimming circuit and lighting device using the same Download PDF

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Publication number
TW201429301A
TW201429301A TW102100372A TW102100372A TW201429301A TW 201429301 A TW201429301 A TW 201429301A TW 102100372 A TW102100372 A TW 102100372A TW 102100372 A TW102100372 A TW 102100372A TW 201429301 A TW201429301 A TW 201429301A
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Taiwan
Prior art keywords
voltage
unit
pulse width
driving circuit
width modulation
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TW102100372A
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Chinese (zh)
Inventor
Chun-Kuang Chen
Po-Shen Chen
Feng-Ling Lin
hui-ying Chen
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Lextar Electronics Corp
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Priority to TW102100372A priority Critical patent/TW201429301A/en
Publication of TW201429301A publication Critical patent/TW201429301A/en

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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
    • H05B45/00Circuit arrangements for operating light emitting diodes [LED]
    • H05B45/10Controlling the intensity of the light
    • H05B45/14Controlling the intensity of the light using electrical feedback from LEDs or from LED modules

Abstract

A dimming circuit and a lighting device using the same are provided. The dimming circuit comprises an interface trigger unit, an average duty cycle calculating unit, a control voltage calculating unit and a comparing unit. The interface trigger unit receives an on-time from each period in a PWM signal. The average duty cycle calculating unit is coupled to the interface trigger unit and calculates a ratio of the on-time to the period. The control voltage calculating unit is coupled to the average duty cycle calculating unit, and calculates a desired voltage according to the ratio. The comparing unit is coupled to the control voltage calculating unit, and sends the desired voltage and a differential voltage to a driving circuit.

Description

調光電路及應用其之發光裝置 Dimming circuit and light emitting device using same
本發明關於一種調光電路及應用其之發光裝置,特別是指一種用於調整發光二極體的調光電路及應用其之發光裝置。 The invention relates to a dimming circuit and a lighting device using the same, in particular to a dimming circuit for adjusting a light emitting diode and a lighting device using the same.
傳統的調光方法係於電路中串接一可變電阻,用以控制流經電路之負載電流,但此電阻會消耗電路中的能量,使得發光效率不佳。 The conventional dimming method is a series connection of a variable resistor in the circuit for controlling the load current flowing through the circuit, but the resistor consumes energy in the circuit, so that the luminous efficiency is not good.
脈寬調變(Pulse Width Modulation,PWM)由於具有雜訊效應較低與耗能較低的優點,故可用於調整照明設備的光線。脈寬調變係採用不連續電流的方式調光,當輸出不是100%時,在脈寬調變每個輸出週期前會有部份的電流為零,呈現暗態。藉由調整暗態與亮態的比例達成所需的調光效果。一般脈寬調變的訊號頻率大於1 kHz以上,高於人眼可視範圍,因此使用者不會感覺到閃爍。 Pulse Width Modulation (PWM) can be used to adjust the light of lighting equipment due to its low noise and low energy consumption. Pulse width modulation is dimmed by discontinuous current. When the output is not 100%, some current will be zero before each output period of pulse width modulation, showing a dark state. The desired dimming effect is achieved by adjusting the ratio of the dark state to the bright state. Generally, the signal width of the pulse width modulation is greater than 1 kHz, which is higher than the visible range of the human eye, so the user does not feel the flicker.
但是,若需要攝影時,如果攝影器材的掃瞄頻率小於調光用脈寬調變訊號的工作頻率,則會發生閃頻(Flicker),影像出現格紋狀現象,使攝像品質失真。 However, if photography is required, if the scanning frequency of the photographic equipment is less than the operating frequency of the pulse width modulation signal for dimming, a flicker will occur, and the image will appear plaid, which will distort the image quality.
此外,當脈寬調變設定為低導通時,也可能因為電流不足,使得光源出現閃爍現象。 In addition, when the pulse width modulation is set to be low, the light source may flicker due to insufficient current.
本發明關於一種調光電路及應用其之發光裝置,可改善閃頻以及低導通時閃爍的問題。 The invention relates to a dimming circuit and a lighting device using the same, which can improve the problem of flickering and flickering during low conduction.
根據本發明之一實施例,提供一種調光電路,包括介面觸發單元、平均工作週期計算單元、控制電壓計算單元以及比較單元。介面觸發單元接收脈寬調變訊號各個週期之脈衝寬度的導通時間。平均工作週期計算單元耦接介面觸發單元,並計算介面觸發單元所輸出之導通時間占週期的比例。控制電壓計算單元耦接平均工作週期計算單元,並依據平均工作週期計算單元所計算出之比例,計算所需電壓。比較單元耦接控制電壓計算單元,並根據控制電壓計算單元所計算出之所需電壓,計算與回授電壓的差值電壓,並傳送所需電壓及差值電壓給驅動電路。 According to an embodiment of the present invention, a dimming circuit is provided, including an interface triggering unit, an average duty cycle calculating unit, a control voltage calculating unit, and a comparing unit. The interface trigger unit receives the on-time of the pulse width of each period of the pulse width modulation signal. The average duty cycle calculation unit is coupled to the interface trigger unit, and calculates a ratio of the on-time of the output of the interface trigger unit to the period. The control voltage calculation unit is coupled to the average duty cycle calculation unit, and calculates the required voltage according to the ratio calculated by the average duty cycle calculation unit. The comparison unit is coupled to the control voltage calculation unit, and calculates a difference voltage with the feedback voltage according to the required voltage calculated by the control voltage calculation unit, and transmits the required voltage and the difference voltage to the drive circuit.
根據本發明之一實施例,提供一種發光裝置,包括發光二極體、驅動電路以及調光電路。驅動電路控制發光二極體發光。調光電路包括介面觸發單元、平均工作週期計算單元、控制電壓計算單元以及比較單元。介面觸發單元接收第一脈寬調變訊號各個週期之脈衝寬度的導通時間。平均工作週期計算單元耦接介面觸發單元,並計算介面觸發單元所輸出之導通時間占週期的比例。控制電壓計算單元耦接平均工作週期計算單元,並依據平均工作週期計算單元所計算出之比例,計算所需電壓。比較單元耦接控制電壓計算單元,並根據控制電壓計算單元所計算出之所需電壓,計算與回授電壓的差值電壓,並傳送所需電壓及差值電壓給驅動電路。其中,驅動電路依據差值電壓補償輸出至發光二極體的控制電壓。控制電壓係依據第二脈 寬調變訊號而產生,第二脈寬調變訊號的頻率大於第一脈寬調變訊號的頻率。 According to an embodiment of the present invention, a light emitting device including a light emitting diode, a driving circuit, and a dimming circuit is provided. The driving circuit controls the light emitting diode to emit light. The dimming circuit includes an interface triggering unit, an average duty cycle calculating unit, a control voltage calculating unit, and a comparing unit. The interface triggering unit receives the on-time of the pulse width of each period of the first pulse width modulation signal. The average duty cycle calculation unit is coupled to the interface trigger unit, and calculates a ratio of the on-time of the output of the interface trigger unit to the period. The control voltage calculation unit is coupled to the average duty cycle calculation unit, and calculates the required voltage according to the ratio calculated by the average duty cycle calculation unit. The comparison unit is coupled to the control voltage calculation unit, and calculates a difference voltage with the feedback voltage according to the required voltage calculated by the control voltage calculation unit, and transmits the required voltage and the difference voltage to the drive circuit. The driving circuit compensates the control voltage output to the LED according to the difference voltage. Control voltage is based on the second pulse The width of the second pulse width modulation signal is greater than the frequency of the first pulse width modulation signal.
為了對本發明之上述及其他方面有更佳的瞭解,下文特舉實施例,並配合所附圖式,作詳細說明如下: In order to provide a better understanding of the above and other aspects of the present invention, the following detailed description of the embodiments and the accompanying drawings
第1圖繪示依據本發明一實施例之調光電路的功能方塊圖。調光電路100包括介面觸發單元110、平均工作週期計算單元120、控制電壓計算單元130以及比較單元140。 FIG. 1 is a functional block diagram of a dimming circuit according to an embodiment of the invention. The dimming circuit 100 includes an interface triggering unit 110, an average duty cycle calculating unit 120, a control voltage calculating unit 130, and a comparing unit 140.
介面觸發單元110係用以接收外部的第一脈寬調變(PWM)訊號S,並將其脈衝寬度的正緣與負緣轉換成觸發訊號,以便進行運算。舉例來說,請參照第2A圖,其繪示一具有正向波形之脈寬調變訊號的電壓與時間關係圖。電壓值上升之處稱為正緣,而電壓值下降之處稱為負緣,一個脈波具有一個正緣與一個負緣。第2A圖所示之PWM訊號包括二個正緣Pn,Pn+1與二個負緣Nn,Nn+1,其通過介面觸發單元後,將會轉換成如第2B圖所示的觸發訊號r,紀錄正緣與負緣的所在位置。 The interface triggering unit 110 is configured to receive an external first pulse width modulation (PWM) signal S, and convert the positive edge and the negative edge of the pulse width into a trigger signal for performing an operation. For example, please refer to FIG. 2A, which illustrates a voltage versus time relationship of a pulse width modulation signal having a forward waveform. The rise of the voltage value is called the positive edge, and the drop of the voltage value is called the negative edge. A pulse wave has a positive edge and a negative edge. The PWM signal shown in FIG. 2A includes two positive edges P n , P n+1 and two negative edges N n , N n+1 , which will be converted into a picture as shown in FIG. 2B after the interface is triggered by the interface. The trigger signal r records the position of the positive and negative edges.
在本實施例中,由於提供的為正向波形之脈寬調變訊號(第2A圖),因此兩個鄰近正緣Pn,Pn+1所間隔的時間即為脈寬調變訊號之週期(period)TPWM,而正緣Pn到下一個負緣Nn所間隔的時間則為此週期之脈波寬度的導通時間(on-time)TON。當提供之脈寬調變訊號為反向波形時(未繪示),則以鄰近兩個負緣的間隔時間為週期,從負緣到下一 個正緣的間隔時間為導通時間。 In this embodiment, since the pulse width modulation signal of the forward waveform is provided (FIG. 2A), the time interval between the two adjacent positive edges P n and P n+1 is the pulse width modulation signal. The period T PWM , and the time interval from the positive edge P n to the next negative edge N n is the on-time T ON of the pulse width of this period. When the pulse width modulation signal is provided as a reverse waveform (not shown), the interval time from the negative edge to the next positive edge is the on time, and the interval time from the negative edge to the next positive edge is the on time.
平均工作週期計算單元120耦接介面觸發單元,用以計算第一脈寬調變訊號S之工作週期(Duty cycle),也就是導通時間占週期的比例。工作週期的計算公式為: The average duty cycle calculation unit 120 is coupled to the interface trigger unit for calculating a duty cycle of the first pulse width modulation signal S, that is, a ratio of the on time to the cycle. The calculation formula for the work cycle is:
其中D表示工作週期,TON表示導通時間,而TPWM表示週期。舉例來說,如果一脈寬調變訊號之週期為1秒,而導通時間占0.2秒,則工作週期為20%。若脈寬調變訊號之週期與導通時間為定值,則各個脈波的工作週期與整個脈寬調變訊號的工作週期相等。若脈寬調變訊號各脈波的週期與導通時間會變動,則平均工作週期計算單元120計算各個脈波的工作週期,求出此些工作週期的一平均值。 Where D represents the duty cycle, T ON represents the on-time, and T PWM represents the cycle. For example, if the period of a pulse width modulation signal is 1 second and the on time is 0.2 seconds, the duty cycle is 20%. If the period and the on-time of the pulse width modulation signal are constant values, the duty cycle of each pulse wave is equal to the duty cycle of the entire pulse width modulation signal. If the period and the on-time of each pulse wave of the pulse width modulation signal change, the average duty cycle calculation unit 120 calculates the duty cycle of each pulse wave, and obtains an average value of the duty cycles.
控制電壓計算單元130耦接平均工作週期計算單元120,根據平均工作週期計算單元120輸出的平均工作週期,計算當輸出電流為直流時的所需電壓V1。舉例來說,若第一脈寬調變訊號S的電壓為5伏特,且平均工作週期為20%時,所需電壓即為5×20%=1伏特。 The control voltage calculation unit 130 is coupled to the average duty cycle calculation unit 120 to calculate the required voltage V 1 when the output current is DC according to the average duty cycle output by the average duty cycle calculation unit 120. For example, if the voltage of the first pulse width modulation signal S is 5 volts and the average duty cycle is 20%, the required voltage is 5×20%=1 volts.
比較單元140耦接控制電壓計算單元130,用以將所需電壓V1傳送給光源之驅動電路,例如是第1圖之驅動電路300,以便進行調光。 The comparison unit 140 is coupled to the control voltage calculation unit 130 for transmitting the required voltage V 1 to the driving circuit of the light source, for example, the driving circuit 300 of FIG. 1 for dimming.
在一實施例中,調光電路100更可包括回授單元150,用以補償電路中損失的能量。回授單元150耦接於比較單元140與光源之驅動電路300之間,用以將驅動電路輸出 給光源的輸出電流轉換成回授電壓V2,再將此回授電壓V2輸出給比較單元140。本實施例中,比較單元140接受回授電壓V2之後,計算此回授電壓V2與所需電壓V1的差值電壓VD,同時傳送所需電壓V1及差值電壓VD給驅動電路300。 In an embodiment, the dimming circuit 100 further includes a feedback unit 150 for compensating for energy lost in the circuit. The feedback unit 150 is coupled between the comparison unit 140 and the driving circuit 300 of the light source for converting the output current outputted by the driving circuit to the light source into the feedback voltage V 2 , and outputting the feedback voltage V 2 to the comparison unit. 140. In this embodiment, after receiving the feedback voltage V 2 , the comparison unit 140 calculates the difference voltage V D between the feedback voltage V 2 and the required voltage V 1 , and simultaneously transmits the required voltage V 1 and the difference voltage V D to Drive circuit 300.
綜合來說,調光電路100可接受頻率從Hz-kHz等不同數量級的脈寬調變調光訊號,並將其轉換為特定的所需電壓V1,進而改變輸出電流為直流的連續電流。維持脈寬調變訊號低損耗的優點,還能改善閃頻與低導通時的光源閃爍問題。 In summary, the dimming circuit 100 can accept a pulse width modulation dimming signal of a different frequency from Hz-kHz and convert it into a specific required voltage V 1 , thereby changing the continuous current whose output current is DC. Maintaining the low loss of the pulse width modulation signal can also improve the flashing of the source when the flash frequency and low conduction.
在一實施例中,調光電路100可用於照明領域。例如請參照第1圖,一發光裝置10包括上述調光電路100、發光二極體200以及驅動電路300。驅動電路300耦接調光電路100與發光二極體200,以接收調光電路100發出的調光訊號(差值電壓VD、所需電壓V1)而產生控制電壓VC驅動發光二極體200。 In an embodiment, the dimming circuit 100 can be used in the field of illumination. For example, referring to FIG. 1, a light-emitting device 10 includes the above-described dimming circuit 100, a light-emitting diode 200, and a driving circuit 300. The driving circuit 300 is coupled to the dimming circuit 100 and the LED diode 200 to receive the dimming signal (difference voltage V D , the required voltage V 1 ) emitted by the dimming circuit 100 to generate a control voltage V C to drive the LED Body 200.
本例中,驅動電路300更可包括整流器310、功率級(power stage)320與低通濾波器(low-pass filter)330。 In this example, the driving circuit 300 further includes a rectifier 310, a power stage 320, and a low-pass filter 330.
整流器310耦接於外接電壓U。當外接電壓U為交流電時,整流器可將其轉換為直流電。 The rectifier 310 is coupled to the external voltage U. When the external voltage U is alternating current, the rectifier can convert it to direct current.
功率級320耦接於整流器310與調光電路100之比較單元140之間,用以根據比較單元140輸出之所需電壓V1與差值電壓VD,將外接電壓U轉換成控制電壓VC。一實施例中,控制電壓VC更可依據驅動電路300的第二脈寬調變訊號(未繪示)產生。此第二脈寬調變訊號較佳但非 限定地為一高頻訊號,其頻率大於第一脈寬調變訊號的頻率。也就是說,不論外部輸入的第一脈寬調變訊號頻率為何,輸出至功率級320的脈寬調變訊號皆為高頻率。一例中,第二脈寬調變序號之頻率大於20 kHz,而第一脈寬調變訊號之頻率小於5 kHz。 The power stage 320 is coupled between the rectifier 310 and the comparison unit 140 of the dimming circuit 100 for converting the external voltage U into the control voltage V C according to the required voltage V 1 and the difference voltage V D output by the comparison unit 140. . In one embodiment, the control voltage V C can be generated according to the second pulse width modulation signal (not shown) of the driving circuit 300. Preferably, the second pulse width modulation signal is a high frequency signal having a frequency greater than a frequency of the first pulse width modulation signal. That is to say, regardless of the first pulse width modulation signal frequency of the external input, the pulse width modulation signal output to the power stage 320 is a high frequency. In one example, the frequency of the second pulse width modulation number is greater than 20 kHz, and the frequency of the first pulse width modulation signal is less than 5 kHz.
低通濾波器330能夠容許低頻信號通過,但減弱頻率高於截止頻率之信號通過,用以使控制電壓之波形趨近於直流。 The low pass filter 330 is capable of allowing low frequency signals to pass, but attenuating signals having a frequency higher than the cutoff frequency to pass the waveform of the control voltage to direct current.
綜上所述,雖然本發明已以實施例揭露如上,然其並非用以限定本發明。本發明所屬技術領域中具有通常知識者,在不脫離本發明之精神和範圍內,當可作各種之更動與潤飾。因此,本發明之保護範圍當視後附之申請專利範圍所界定者為準。 In conclusion, the present invention has been disclosed in the above embodiments, but it is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.
10‧‧‧發光裝置 10‧‧‧Lighting device
100‧‧‧調光電路 100‧‧‧ dimming circuit
110‧‧‧介面觸發單元 110‧‧‧Interface trigger unit
120‧‧‧平均工作週期計算單元 120‧‧‧Average duty cycle calculation unit
130‧‧‧控制電壓計算單元 130‧‧‧Control voltage calculation unit
140‧‧‧比較單元 140‧‧‧Comparative unit
150‧‧‧回授單元 150‧‧‧return unit
200‧‧‧發光二極體 200‧‧‧Lighting diode
300‧‧‧驅動電路 300‧‧‧ drive circuit
310‧‧‧整流器 310‧‧‧Rectifier
320‧‧‧功率級 320‧‧‧Power level
330‧‧‧低通濾波器 330‧‧‧low pass filter
Nn,Nn+1‧‧‧負緣 N n , N n+1 ‧‧‧ negative margin
Pn,Pn+1‧‧‧正緣 P n , P n+1 ‧‧‧
r‧‧‧觸發訊號 R‧‧‧ trigger signal
S‧‧‧第一脈寬調變訊號 S‧‧‧First pulse width modulation signal
TON‧‧‧導通時間 T ON ‧‧‧ On time
TPWM‧‧‧週期 T PWM ‧‧ ‧cycle
U‧‧‧外接電壓 U‧‧‧ external voltage
V1‧‧‧所需電壓 V 1 ‧‧‧required voltage
V2‧‧‧回授電壓 V 2 ‧‧‧Responsive voltage
VC‧‧‧控制電壓 V C ‧‧‧Control voltage
VD‧‧‧差值電壓 V D ‧‧ ‧ difference voltage
第1圖繪示依據本發明一實施例之調光電路的功能方塊圖。 FIG. 1 is a functional block diagram of a dimming circuit according to an embodiment of the invention.
第2A圖繪示一具有正向波形之脈寬調變訊號的電壓與時間關係圖。 FIG. 2A is a diagram showing voltage versus time of a pulse width modulation signal having a forward waveform.
第2B圖繪示第2A圖之脈寬調變訊號通過本發明之介面觸發單元後的示意圖。 FIG. 2B is a schematic diagram showing the pulse width modulation signal of FIG. 2A after passing through the interface trigger unit of the present invention.
10‧‧‧發光裝置 10‧‧‧Lighting device
100‧‧‧調光電路 100‧‧‧ dimming circuit
110‧‧‧介面觸發單元 110‧‧‧Interface trigger unit
120‧‧‧平均工作週期計算單元 120‧‧‧Average duty cycle calculation unit
130‧‧‧控制電壓計算單元 130‧‧‧Control voltage calculation unit
140‧‧‧比較單元 140‧‧‧Comparative unit
150‧‧‧回授單元 150‧‧‧return unit
200‧‧‧發光二極體 200‧‧‧Lighting diode
300‧‧‧驅動電路 300‧‧‧ drive circuit
310‧‧‧整流器 310‧‧‧Rectifier
320‧‧‧功率級 320‧‧‧Power level
330‧‧‧低通濾波器 330‧‧‧low pass filter
S‧‧‧第一脈寬調變訊號 S‧‧‧First pulse width modulation signal
U‧‧‧外接電壓 U‧‧‧ external voltage
V1‧‧‧所需電壓 V 1 ‧‧‧required voltage
V2‧‧‧回授電壓 V 2 ‧‧‧Responsive voltage
VC‧‧‧控制電壓 V C ‧‧‧Control voltage
VD‧‧‧差值電壓 V D ‧‧ ‧ difference voltage

Claims (10)

  1. 一種發光二極體調光電路,包括:一介面觸發單元,係接收一脈寬調變(PWM)訊號之複數個週期之各一脈衝寬度的一導通時間;一平均工作週期(duty cycle)計算單元,耦接該介面觸發單元,用以計算該介面觸發單元所輸出之該些導通時間占該些週期的一比例;一控制電壓計算單元,耦接該平均工作週期計算單元,並依據該平均工作週期計算單元所計算出之該比例,計算一所需電壓;以及一比較單元,耦接該控制電壓計算單元,並根據該控制電壓計算單元所計算出之該所需電壓,計算其與一回授電壓的一差值電壓,並傳送該所需電壓及該差值電壓給一發光二極體驅動電路。 A light-emitting diode dimming circuit includes: an interface triggering unit that receives an on-time of each pulse width of a plurality of cycles of a pulse width modulation (PWM) signal; and an average duty cycle calculation The unit is coupled to the interface trigger unit for calculating a ratio of the on-times output by the interface trigger unit to the periods; a control voltage calculation unit coupled to the average duty cycle calculation unit, and based on the average The ratio calculated by the duty cycle calculation unit calculates a required voltage; and a comparison unit coupled to the control voltage calculation unit and calculates the required voltage according to the control voltage calculation unit, and calculates the required voltage A difference voltage of the voltage is fed back, and the required voltage and the difference voltage are transmitted to a light emitting diode driving circuit.
  2. 如申請專利範圍第1項所述之發光二極體調光電路,更包括:一回授單元,耦接於該發光二極體驅動電路與該比較單元之間,用以將該發光二極體驅動電路輸出給一發光二極體的一輸出電流轉換成該回授電壓,並輸出該回授電壓給該比較單元。 The illuminating diode dimming circuit of claim 1, further comprising: a feedback unit coupled between the illuminating diode driving circuit and the comparing unit for illuminating the illuminating diode An output current output from the body driving circuit to a light emitting diode is converted into the feedback voltage, and the feedback voltage is output to the comparing unit.
  3. 如申請專利範圍第1項所述之發光二極體調光電路,其中該介面觸發單元將該脈寬調變訊號之各該脈衝寬度的正緣與負緣轉換成複數個觸發訊號,並由該些觸發訊號計算出該些導通時間。 The illuminating diode dimming circuit of claim 1, wherein the interface triggering unit converts a positive edge and a negative edge of each pulse width of the pulse width modulation signal into a plurality of trigger signals, and The trigger signals calculate the on-times.
  4. 一種無閃頻的發光裝置,包括:一發光二極體;一驅動電路,係控制該發光二極體發光;一調光電路,包括:一介面觸發單元,係取得一第一脈寬調變訊號之複數個週期的各一脈衝寬度的一導通時間;一平均工作週期計算單元,耦接該介面觸發單元,並計算該介面觸發單元所輸出之該些導通時間占該些週期的一比例;一控制電壓計算單元,耦接該平均工作週期計算單元,並依據該平均工作週期計算單元所輸出之該比例,計算一所需電壓;及一比較單元,耦接該控制電壓輸出單元,並根據該控制電壓計算單元所計算出之該所需電壓,計算該所需電壓與該發光二極體之一回授電壓的一差值電壓,並傳送該所需電壓及該差值電壓給該驅動電路;其中該驅動電路依據該差值電壓補償輸出至該發光二極體的一控制電壓,其中該控制電壓依據一第二脈寬調變訊號而產生,該第二脈寬調變訊號的一頻率大於該第一脈寬調變訊號的一頻率。 A light-emitting device without a flash frequency, comprising: a light-emitting diode; a driving circuit for controlling the light-emitting diode; and a light-modulating circuit comprising: an interface triggering unit for obtaining a first pulse width modulation An on-time of each pulse width of the plurality of periods of the signal; an average duty cycle calculation unit coupled to the interface trigger unit, and calculating a ratio of the on-times output by the interface trigger unit to the periods; a control voltage calculation unit coupled to the average duty cycle calculation unit, and calculating a required voltage according to the ratio output by the average duty cycle calculation unit; and a comparison unit coupled to the control voltage output unit, and according to Calculating the required voltage calculated by the control voltage calculation unit, calculating a difference voltage between the required voltage and one of the feedback voltages of the LED, and transmitting the required voltage and the difference voltage to the driving a circuit, wherein the driving circuit compensates a control voltage outputted to the LED according to the difference voltage, wherein the control voltage is based on a second pulse width modulation signal Generating a second frequency of the PWM signal is greater than a first frequency of the PWM signals.
  5. 如申請專利範圍第4項所述之無閃頻的發光裝置,其中該調光電路更包括:一回授單元,耦接於該驅動電路與該比較單元之間,用以將該驅動電路輸出給該發光二極體的一輸出電流轉換成該回授電壓,並輸出該回授電壓給該比較單元。 The illuminating device of the fourth embodiment of the invention, wherein the dimming circuit further comprises: a feedback unit coupled between the driving circuit and the comparing unit for outputting the driving circuit An output current of the light emitting diode is converted into the feedback voltage, and the feedback voltage is output to the comparison unit.
  6. 如申請專利範圍第4項所述之無閃頻的發光裝置,其中該介面觸發單元將該第一脈寬調變訊號之各該脈衝寬度的正緣與負緣轉換成複數個觸發訊號,並由該些觸發訊號計算出該些導通時間。 The device of claim 4, wherein the interface triggering unit converts a positive edge and a negative edge of each pulse width of the first pulse width modulation signal into a plurality of trigger signals, and The on-times are calculated from the trigger signals.
  7. 如申請專利範圍第4項所述之無閃頻的發光裝置,其中該驅動電路的該第二脈寬調變訊號之該頻率大於20 kHz,該第一脈寬調變訊號之該頻率小於5 kHz。 The strobe-free illuminating device of claim 4, wherein the frequency of the second pulse width modulation signal of the driving circuit is greater than 20 kHz, and the frequency of the first pulse width modulation signal is less than 5 kHz.
  8. 如申請專利範圍第4項所述之無閃頻的發光裝置,其中該驅動電路包括一整流器,將該外接電壓由交流電轉換為直流電。 The flash-free lighting device of claim 4, wherein the driving circuit comprises a rectifier for converting the external voltage from alternating current to direct current.
  9. 如申請專利範圍第8項所述之無閃頻的發光裝置,其中該驅動電路更包括一功率級(power stage),該功率級根據該比較單元輸出之該所需電壓及該差值電壓,將一外接電壓轉換成該發光二極體的該控制電壓。 The flash-free lighting device of claim 8, wherein the driving circuit further comprises a power stage, wherein the power level is based on the required voltage and the difference voltage output by the comparing unit. An external voltage is converted to the control voltage of the light emitting diode.
  10. 如申請專利範圍第8項所述之無閃頻的發光裝置,其中該驅動電路更包括一低通濾波器(Low-pass filter),使該控制電壓之波形趨近於直流。 The flash-free illumination device of claim 8, wherein the driving circuit further comprises a low-pass filter to bring the waveform of the control voltage to direct current.
TW102100372A 2013-01-07 2013-01-07 Dimming circuit and lighting device using the same TW201429301A (en)

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